Interfacial viscosification of aqueous system utilizing sulfonated ionomers

ABSTRACT

The present invention relates to a process for the viscosification of an aqueous liquid which includes the steps of forming a solvent system of an organic liquid or oil and a polar cosolvent, the polar cosolvent being less than about 15 weight percent of the solvent system, a viscosity of the solvent system being less than about 100 cps; dissolving a neutralized sulfonated polymer in the solvent system to form a solution, a concentration of the neutralized sulfonated polymer in the solution being about 0.01 to about 0.5 weight percent, a viscosity of the solution being less than about 200 cps; and admixing or contacting said solution with about 5 to about 500 volume percent water, the water being immiscible with the organic liquid and the polar cosolvent and neutralized sulfonated polymer transferring from the organic liquid to the water phase, thereby causing the water phase to thicken.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for the viscosification of anaqueous liquid which includes the steps of forming a solvent system ofan organic liquid or oil and a polar cosolvent, the polar cosolventbeing less than about 15 weight percent of the solvent system, aviscosity of the solvent system being less than about 1,000 cps;dissolving a neutralized sulfonated polymer (water insoluble) in thesolvent system to form a solution, a concentration of the neutralizedsulfonated polymer in the solution being about 0.01 to about 0.5 weightpercent, a viscosity of the solution being less than about 200 cps; andadmixing or contacting said solution with about 5 to about 500 volumepercent water, the water being immiscible with the organic liquid andthe polar cosolvent and neutralized sulfonated polymer transferring fromthe organic liquid to the water phase, thereby causing the water phaseto gel (i.e. thicken).

2. Description of the Prior Art

There are many applications for very viscous or gelled solutions ofpolymers in water which are quite diverse. There are also a number ofphysical and chemical techniques for preparing such systems. The presentinvention is concerned with a process for gelling an aqueous system bycontacting the aqueous system with a relatively low viscosity, organicliquid solution of an ionic polymer. The potential applications for thisprocess and the products derived therefrom will be evident in theinstant application. Some of these applications are as a viscosifier foraqueous solutions, for viscosification of aqueous acid and inorganicsalt solutions, as a fluid loss additive, in enhanced oil recovery, as aviscous foamer in oil well applications, as a water shut-off means inoil well applications, as a spacer and soluble pig in oil wellapplications and as a friction reducer in transferring liquid through apipe.

The instant invention differs from a number of applications, Ser. Nos.223,482; 136,837; and 106,027, filed by Robert Lundberg et al, one ofthe instant inventors. These previously filed applications were directedto the gelling of the organic liquid by a water insoluble, neutralizedsulfonated polymer whereas the instant invention is directed to thegelling of an aqueous phase. Quite unexpectedly, it has been discoveredthat when the concentration of the sulfonated polymer in solution ismaintained in a critical concentration range of 0.01 to 0.5 weightpercent of the total volume of solvent, which is a mixture of nonpolarorganic liquid and a polar cosolvent, is agitated with an aqueoussolution, a transfer of the polar solvent and water insolubleneutralized sulfonated polymer from the organic liquid phase to thewater phase occurs. The water insoluble neutralized sulfonated polymercauses the water phase to gel, wherein the neutralized sulfonatedpolymer is insoluble in the water phase. In the previously filed patentapplications, substantial viscosification of the nonpolar organic liquidphase did not occur until the concentration of the neutralizedsulfonated polymer was sufficiently high enough to permit chainentanglement of adjacent polymer molecules thereby completely fillingthe solvent space. The gelation of the aqueous phase of the instantinvention does not occur by this previously described mechanism becausethe resultant concentration of water insoluble, neutralized sulfonatedpolymer is not sufficiently high enough to permit chain entanglement.The mechanism of gelation of the aqueous phase, as defined in theinstant invention, occurs by the formation of macroscopic, sphericalpolymer membranes or films dispersed throughout the aqueous fluid, (i.e.interfacial viscosification) wherein large volumes of the water of theaqueous liquid are encapsulated within a series of minute polymer bags.

The instant invention describes a process which permits (1) thepreparation of polymer solutions of sulfonated polymers in organicliquid having reasonably low viscosities (i.e., less than about 200cps); and (2) the preparation of extremely viscous solutions or gels ofan aqueous fluid from such solutions by a process of mixing orcontacting water with the polymer solution. These operations areachieved by the use of the appropriate concentration; 0.01 to 0.5 weightpercent of water insoluble, neutralized sulfonated polymers, having lowconcentrations of ionic groups present, preferably metal sulfonategroups. Such polymers are described in detail in a number of U.S.Patents (U.S. Pat. Nos. 3,836,511; 3,870,841; 3,847,854; 3,642,728; and3,921,021) which are herein incorporated by reference. These polymerspossess unusual solution characteristics some of which are described inU.S. Pat. No. 3,931,021. Specifically, these polymers, such as lightlysulfonated polystyrene, containing about 2 mole percent sodium sulfonatependant to the aromatic groups, are typically not soluble in solventscommonly employed for polystyrene itself. However, the incorporation ofmodest levels of polar cosolvents permit the rapid dissolution of suchionic polymers to form homogeneous solutions of moderate viscosity.

In the instant process, the role of the polar cosolvent is that ofsolvating the ionic groups while the main body of the solvent interactswith the polymer backbone. For example, xylene is an excellent solventfor the polystyrene backbone and when combined with 5 percent methanolwill dissolve, readily and rapidly, the previous example of lightlysulfonated polystyrene.

The remarkable and surprising discovery of the instant invention is thatwhen small (or large) amounts of water are combined and mixed withsolutions of ionic polymers dissolved at low concentrations (0.01 to 0.5weight percent) in such mixed solvent systems as those described above,a phase transfer of the water insoluble, neutralized sulfonated polymerand cosolvent occurs from the nonpolar organic liquid phase to the waterphase, wherein the water insoluble, neutralized sulfonated polymerscause the water phase to gel. Indeed, it is possible to achieveincreases in viscosity of the water phase by factors of 10³ (1,000) ormore by the addition of only 5 to 15 percent water based on the polymersolution volume. This unusual behavior is postulated to arise from theremoval of the polar cosolvent and water insoluble, neutralizedsulfonated polymer from the organic liquid phase into the separateaqueous phase which then gels.

SUMMARY OF THE INVENTION

The present invention relates to a process for the gelation of anaqueous liquid which includes the steps of forming a solvent system ofan organic liquid or oil and a polar cosolvent. The polar cosolventbeing less than about 15 weight percent of the solvent system with aviscosity of the solvent system being less than about 100 cps;subsequently dissolving a neutralized sulfonated polymer in the solventsystem to form a solution with a concentration of the neutralizedsulfonated polymer in the solution being about 0.01 to about 0.5 weightpercent. The viscosity of the solution being less than about 200 cps.Admixing or contacting said solution with about 5 to about 500 volumepercent water, the water being immiscible with the organic liquid andthe polar cosolvent and neutralized sulfonated polymer transferring fromthe organic liquid to the water phase, thereby causing the water phaseto gel (i.e. thicken).

Accordingly, it is a primary object of the instant invention to describean economical process for forming a highly viscous or gelled aqueoussolution having a viscosity from about 50 to about 1,000 cps.

A further object of the instant invention is to provide a process forforming a gel solution which can be used as a viscosifier for aqueoussystems or aqueous acid systems, and friction reducers for controllingthe flow and aqueous fluid through a pipe.

A still further object of the instant invention is to employ the instantprocess as an integral part of well control procedures such as enhancedoil recovery, water shut-off means, viscous foams and spacers andsoluble pigs.

GENERAL DESCRIPTION

The present invention relates to a process for the gelation of anaqueous liquid which includes the steps of forming a solvent system ofan organic liquid or oil and a polar cosolvent. The polar cosolventbeing less than about 15 weight percent of the solvent system with aviscosity of the solvent system being less than about 100 cps.Subsequently dissolving a neutralized sulfonated polymer in the solventsystem to form a solution with a concentration of the neutralizedsulfonated polymer in the solution being about 0.01 to about 0.5 weightpercent. The viscosity of the solution being less than about 200 cps.Admixing or contacting said solution with about 5 to about 500 volumepercent water, the water being immiscible with the organic liquid andthe polar cosolvent and neutralized sulfonated polymer transferring fromthe organic liquid to the water phase, thereby causing the water phaseto gel.

The gelled aqueous phase having a viscosity greater than 50 cps isformed by the addition of water to a water insoluble solution whichcomprises a water insoluble, neutralized sulfonated polymer, a nonpolarorganic liquid and a polar cosolvent, wherein the solution has aviscosity less than 200 cps. The concentration of neutralized sulfonatedpolymer in the solution is 0.01 to 0.5 weight percent. Upon the additionof water to the solution, the polar cosolvent and water insoluble,neutralized sulfonated polymer rapidly transfers from the solution tothe aqueous water which undergoes immediate gelation. The nonpolarorganic liquid can be removed from the gel by conventional liquidextraction methods. The formation of the aqueous fluid or water having aviscosity of at least 50 cps from the organic solution having aviscosity less than 200 cps, can be quite rapid in the order of lessthan 1 minute to about 24 hours, more preferably less than 1 minute toabout 30 minutes, and most preferably less than 1 minute to about 10minutes, however, this depends on temperature, shear, solvent type, etc.

The component materials of the instant process generally include a waterinsoluble, ionomeric polymer such as a water insoluble, neutralizedsulfonated polymer at a critical concentration level of 0.01 to 0.5weight percent, a nonpolar organic liquid, polar cosolvent and water.

Gelation of an aqueous phase does not occur, if one employs aconventional unsulfonated polymer or a water soluble, neutralizedsulfonated polymer in place of the water insoluble, neutralizedsulfonated polymer, but rather only classical phase separation occurs.

In the instant invention, the gelation of the aqueous phase occurs bythe formation of geometrically shaped spheres of the water insoluble,neutralized sulfonated polymer within the aqueous phase, wherein thewater is encapsulated within these geometrically shaped spheres(so-called water-in-water pseudo-emulsion). During the process,approximately 10 weight percent of the nonpolar organic liquid alsotransfers to the aqueous phase and is encapsulated within thesegeometrically shaped spheres.

A second aspect of the instant invention relates to the use of thesematerials in aqueous systems containing large concentrations of salt oracid. The sulfonated polystyrenes which are the preferred embodiment ofthis invention lose their effectiveness (i.e., as a water-in-waterpseudo-emulsion former) in salt water, but are enhanced inacid-containing water. More specifically, it has been found that asuitable nonionic surfactant must be employed with the water insoluble,sulfonated polystyrene to give formulations which are effective inproducing these water-in-water pseudo-emulsions in high concentrationsof salt water. In acidic solutions, the nonionic surfactant is notneeded for stability (25° C.), however, the viscosity of thesepseudo-emulsion systems tends to increase significantly with theaddition of small amounts of the nonionic material (typically <0.04g/l).

In general, the water insoluble ionomeric polymer will comprise fromabout 10 to about 200 meq. pendant ionomeric groups per 100 grams ofpolymer, more preferably from 10 to 100 meq. pendant ionomeric groups.The ionic groups may be conveniently selected from the groups consistingof carboxylate, phosphonate, and sulfonate, preferably sulfonate groups.In most instances, the ionomers utilized in the instant invention areneutralized with the basic materials selected from Groups IA, IIA, IBand IIB of the Periodic Table of Elements and lead, tin and antimony, aswell as ammonium and amine counterions. Ionic polymers which are subjectto the process of the instant invention are illimitable and include bothplastic and elastic polymers. Specific polymers include sulfonatedpolystyrene, sulfonated t-butyl styrene, sulfonated ethylene copolymers,sulfonated propylene copolymers, sulfonated styrene/acrylonitrilecopolymers, sulfonated styrene/methyl methacrylate copolymers,sulfonated block copolymers of styrene/ethylene oxide, acrylic acidcopolymers with styrene, sulfonated polyisobutylene, sulfonatedethylene-propylene terpolymers, sulfonated polyisoprene, and sulfonatedelastomers and their copolymers. The preferred polymers of the instantinvention are ethylene-propylene terpolymers and polystyrene, whereinpolystyrene is most preferred.

Neutralization of the cited polymers with appropriate metal hydroxides,metal acetates, metal oxides, or ammonium hydroxide etc., can beconducted by means well-known in the art. For example, the sulfonationprocess as with Butyl rubber containing a small 0.3 to 1.0 mole percentunsaturation can be conducted in a suitable solvent such as toluene,with acetyl sulfate as the sulfonated agent, such as described in U.S.Pat. No. 3,836,511. The resulting sulfonic acid derivative can then beneutralized with a number of different neutralization agents such as asodium phenolate and similar metal salts. The amounts of suchneutralization agents employed will normally be equal stoichiometricallyto the amount of free acid in the polymer plus any unreacted reagentwhich is still present. It is preferred that the amount of neutralizingagent be equal to the molar amount of sulfonating agent originallyemployed plus 10 percent more to insure full neutralization. The use ofmore of such neutralization agent is not critical. Sufficientneutralization agent is necessary to effect at least 50 percentneutralization of the sulfonic acid groups present in the polymer,preferably at least 90 percent, and most preferably essentially completeneutralization of such acid groups should be effected.

The degree of neutralization of said ionomeric groups may vary from 0(free acid form) to greater than 100 mole percent, preferably 50 to 100percent. With the utilization of neutralized ionomers in this instantinvention, it is preferred that the degree of neutralization besubstantially complete, that is with no substantial free acid presentand without substantial excess of the base other than that needed toinsure neutralization. The neutralized ionomers possess greater thermalstability compared to its acid form. Thus, it is clear that the polymerswhich are normally utilized in the instant invention comprisesubstantially neutralized pendant groups, and in fact, an excess of theneutralizing material may be utilized without defeating the objects ofthe instant invention.

The ionomeric polymers of the instant invention may vary in numberaverage molecular weight from 1,000 to 10,000,000 preferably from 5,000to 500,000, most preferably from 10,000 to 200,000. These polymers maybe prepared by methods known in the art, for example, see U.S. Pat. No.3,642,728, hereby incorporated by reference.

The preferred ionic copolymers for use in the instant invention, e.g.,sulfonated polystyrene and substituted derivatives thereof, may beprepared by the procedures described in U.S. Pat. No. 3,870,841, filedOct. 2, 1972, in the names of H. S. Makowski, R. D. Lundberg and G. H.Singhal, hereby incorporated by reference.

The water insoluble, ionomeric polymers may be incorporated into theorganic liquid at a level of from 0.01 to 0.5 weight percent and morepreferably from 0.01 to 0.4 weight percent, based on the organic liquidand the polar cosolvent.

Specific examples of preferred ionomeric polymers which are useful inthe instant invention include sulfonated polystyrene, sulfonatedpoly-t-butyl styrene, sulfonated polyethylene (substantiallynoncrystalline), and sulfonated ethylene copolymers, sulfonatedpolypropylene (substantially noncrystalline), and sulfonatedpolypropylene copolymers, sulfonated styrenemethyl methacrylatecopolymers, (styrene)-acrylic acid copolymers, sulfonatedpolyisobutylene, sulfonated ethylene-propylene terpolymers, sulfonatedpolyisoprene, sulfonated polyvinyl toluene and sulfonated polyvinyltoluene copolymers.

The ionomeric polymers of the instant invention may be prepared prior toincorporation into the organic solvent, or by neutralization of the acidfrom a situ. For example, preferably the acid derivative is neutralizedimmediately after preparation. For example, if the sulfonation ofpolystyrene is conducted in solution, then the neutralization of thatacid derivative can be conducted immediately following the sulfonationprocedure. The neutralized polymer may then be isolated by meanswell-known to those skilled in the art, i.e., coagulation, steamstripping, or solvent evaporation, because the neutralized polymer hassufficient thermal stability to be dried for employment at a later timein the process of the instant invention. It is well-known that theunneutralized sulfonic acid derivatives do not possess good thermalstability and the above operations avoid that problem.

It is also possible to neutralize the acid form of these polymers insitu; however, this is not a preferred operation, since in situneutralization requires preparation of the sulfonic acid in the organicliquid which is to be subjected to the instant process, or the acid formof the ionic polymer must be dissolved in said organic liquid. Thelatter approach may involve handling of an acid form of an ionic polymerwhich has limited thermal stability. Therefore, it is quite apparentthat the preparation and isolation of a neutralized ionic polymeraffords the maximum latitude in formulation, less problems in handlingpolymers of limited thermal stability and maximum control over the finalmixture of ionic polymer, polar cosolvent and organic liquid.

The organic liquids, which may be utilized in the instant invention, areselected with relation to the ionic polymer and vice-versa. The organicliquid is selected from the group consisting essentially of aromatichydrocarbons, cyclic aliphatic ethers, aliphatic ethers, or organicaliphatic esters and mixtures thereof.

Specific examples of organic liquids to be employed with the varioustypes of polymers are:

    ______________________________________                                        Polymer           Organic Liquid                                              ______________________________________                                        sulfonated polystyrene                                                                          benzene, toluene, ethyl                                                       benzene, methylethyl                                                          ketone, xylene, styrene,                                                      ethylenedichloride,                                                           methylene chloride.                                         sulfonated poly-t-butyl-                                                                        benzene, toluene, xylene,                                   styrene           ethyl benzene, styrene,                                                       t-butyl styrene, aliphatic                                                    oils, aromatic oils, hexane,                                                  heptane, decane, nonane.                                    sulfonated ethylene-                                                                            pentane, aliphatic and                                      propylene terpolymer                                                                            aromatic solvents, oils                                                       such as Solvent "100                                                          Neutral", "150 Neutral"                                                       and similar oils, benzene,                                                    diesel oil, toluene,                                                          xylene, ethyl benzene,                                                        pentane, hexane, heptane,                                                     octane, isooctane, nonane,                                                    decane aromatic solvents,                                                     ketone solvents.                                            sulfonated styrene-methyl-                                                                      dioxane, halogenated ali-                                   methacrylate copolymer                                                                          phatics, e.g., methylene                                                      chloride, tetrahydrofuran.                                  sulfonated polyisobutylene                                                                      saturated aliphatic hydro-                                                    carbons, diisobutylene,                                                       triisobutylene, aromatic                                                      and alkyl substituted                                                         aromatic hydrocarbons,                                                        chlorinated hydrocarbons,                                                     n-butyl ether, n-amyl,                                                        ether, methyl oleate,                                                         aliphatic oils, oils pre-                                                     dominantly paraffinic                                                         in nature and mixtures                                                        containing naphthenic                                                         hydrocarbons. "Solvent 100                                                    Neutral", "Solvent 150                                                        Neutral" and all related                                                      oils, low molecular weight                                                    polymeric oils such as                                                        squalene, white oils and                                                      process oils having 60                                                        percent or less aromatic                                                      content.                                                    sulfonated polyvinyl                                                                            toluene, benzene, xylene,                                   toluene           cyclohexane, ethyl benzene,                                                   styrene, methylene chlo-                                                      ride, ethylene dichloride.                                  ______________________________________                                    

The method of the instant invention includes incorporating a polarcosolvent, for example, a polar cosolvent in the mixture of organicliquid and water insoluble ionomer to solubilize the pendant ionomericgroups. The polar cosolvent will have a solubility parameter of at least10.0, more preferably at least 11.0 and is water miscible and maycomprise from 0.1 to 15.0 weight percent, preferably 0.1 to 5.0 weightpercent of the total mixture of organic liquid, water insolubleionomeric polymer, and polar cosolvent. The solvent system of polarcosolvent and organic liquid in which the water insoluble neutralizedsulfonated (ionomeric) polymer is dissolved contains less than about 10weight percent of the polar cosolvent, more preferably about 0.1 toabout 5.0 weight percent, and most preferably about 0.1 to about 5.0weight percent. The viscosity of the solvent system is less than about1,000 cps, more preferably less than about 800 cps and most preferablyless than about 500 cps.

Normally, the polar cosolvent will be a liquid at room temperature;however, this is not a requirement. It is preferred, but not required,that the polar cosolvent be soluble or miscible with the organic liquidat the levels employed in this invention. The polar cosolvent isselected from the group consisting essentially of water solublealcohols, amines, di- or trifunctional alcohols, amides, acetamides,phosphates, or lactones and mixtures thereof. Especially preferred polarcosolvents are aliphatic alcohols such as methanol, ethanol, n-propanol,isopropanol, 1,2-propane diol, monoethyl ether of ethylene glycol, andn-ethylformamide.

The amount of water added to the solution of water insoluble,neutralized sulfonated polymer, organic liquid and polar cosolventhaving a viscosity of less than about 2,000 cps, is about 5 to about 500volume percent of water, more preferably about 10 to about 300 volumepercent water, most preferably about 10 to about 200 volume percentwater.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following examples will demonstrate the performance of sulfonatedpolystyrene of varying sulfonate levels in several specific aqueousenvironments.

EXAMPLE 1

It has been observed that under certain conditions, a hydrocarbonsolution containing a low concentration of a sulfonated polystyrene orsulfonated EPDM is mildly agitated with water for a short period oftime, a pseudo-emulsion is formed. In the initial formation stage, thetype of pseudo-emulsion produced in these systems has a continuousaqueous phase while the hydrocarbon medium is the dispersed phase. It isbelieved that the sulfonated polymer stabilizes the hydrocarbon/waterinterface. Upon standing for a short period of time after mixing hasoccurred, it is observed that approximately 90 percent of the initialhydrocarbon solvent can be separated from the system leaving behind apseudoemulsion system characterized as a water-in-water pseudoemulsion.Addition of a small amount of nonionic surfactant can be added tofacilitate this process. Experimental evidence indicates that freepassage of nonpolar organic solvent occurs through the sulfonatedpolymer membrane and the hydrocarbon solvent is replaced within eachsphere by water as the nonpolar, organic solvent passes through themembrane.

As shown in Table I, the essential material needed for the formation ofa pseudo-emulsion system in a hydrocarbon/water environment is the waterinsoluble, neutralized sulfonated polymer. Table I shows that theaddition of water to a No. 2 diesel oil (or xylene) solution containingtridecyl alcohol as a cosolvent and/or unsulfonated EPDM (Socabu 55) orpolystyrene (Styron 666) results in a classic phase separation of thehydrocarbon and water phases. On the other hand, spontaneous formationof a pseudo-emulsion system occurs in the presence of the sulfonatedpolymer. In addition, it has been observed that more stablepseudo-emulsion systems are produced with increasing sulfonation level.The nature of the counterion does not impair the interfacial activity ofthe polymer.

Further confirmation of the interfacial activity of these sulfonatedpolymers can be obtained utilizing viscosity measurements. The viscosityof several water-in-water pseudo-emulsions as a function of the polymerconcentration is shown in Table II. It is readily apparent that due tothe particular "macroscopic" structures formed in the aqueous phase,significant viscosification occurs as compared to the dissolution of awater soluble polymer of equivalent molecular weight and concentration.The viscosity of the pseudo-emulsion system at high polymer levelsrises, while within the concentration range between approximately 1 and5 g/l, the viscosity is essentially constant. Only when rather lowpolymer levels are reached does the viscosity begin to decline again. Acomparison of the EPDM and polystyrene data indicates that the nature ofthe backbone chain may have little influence on the viscosity of thesystem, while the sulfonate level is of paramount importance. Theseresults can be rationalized by assuming that the sulfonated polymerresides at the water-water interface. This latter observation issupported through the use of light microscopy. Under low magnification(approximately 100X) the structural details of the pseudo-emulsionsystem can be observed. In the first place, a large number of spheresconstitutes a typical pseudo-emulsion system. Secondly, eachpseudo-emulsion particle is a spherical structure in which a largevolume of water is contained with the polymer film. The continuous phaseoutside of each particle is identical in composition to the internalaqueous phase.

EXAMPLE 2

Table II shows the relationship between the viscosity of thepseudo-emulsion phase, formed with polystyrene containing varioussulfonation levels, as a function of polymer concentration. Theviscosity tends to rise at very low polymer concentrations as wasobserved in FIG. 1. Outside of this concentration regime, the viscosityremains constant to rather high polymer levels (˜0.5 g/dl.) Theviscosity of the pseudo-emulsion at a particular polymer concentrationdoes increase with higher sulfonation levels. Undoubtedly, thisobservation is related to both the sphere size and packing within theaqueous phase.

                  TABLE I                                                         ______________________________________                                        FORMATION OF WATER-IN-WATER                                                   PSEUDO-EMULSION (50 HYDROCARBON/50 WATER)                                                             Water/Water                                                                   Pseudo-Emulsion                                       Material                Formed                                                ______________________________________                                        Tridecyl Alcohol        No                                                    Socabu 55 or Styron 666 No                                                    Socabu 55/Tridecyl Alcohol                                                                            No                                                    Zinc Neutralized (10-30 meq.) EPDM                                                                    Yes                                                   Magnesium and Calcium Neutralized                                                                     Yes                                                   (10 meq.) EPDM                                                                Magnesium and Calcium Neutralized                                                                     Yes                                                   (10 meq.) EPDM Tridecyl Alcohol                                               Unneutralized Sulfonated (25 meq.) EPDM                                                               Yes                                                   Tridecyl Alcohol                                                              Sodium Sulfonated (1-6 mole %) Polystyrene                                                            Yes                                                   Zinc Sulfonated (1-3 mole %) Polystyrene                                                              Yes                                                   ______________________________________                                    

                  TABLE II                                                        ______________________________________                                        VISCOSITY* - POLYMER CONCENTRATION DATA                                       OF A TYPICAL PSEUDO-EMULSION SYSTEM                                                           Polymer Concentration                                                                         Viscosity                                     Material        (g/l)           (cps)                                         ______________________________________                                        Sulfonated Polystyrene                                                                        0.25            210                                           (Sodium Salt - 1.7 mole %)                                                                    0.5             295                                                           1.25            315                                                           2.5             320                                                           5.0             340                                           Sulfonated EPDM 0.50            160                                           (Magnesium Salt - 10 meq.)                                                                    1.25            204                                                           2.5             210                                                           5.0             210                                           ______________________________________                                         *Viscosity measured with a Brookfield ® viscometer at 30 RPM.        

                  TABLE III                                                       ______________________________________                                        VISCOSITY* - POLYMER CONCENTRATION DATA OF                                    SEVERAL PSEUDO-EMULSION SYSTEMS FORMED                                        WITH SEVERAL SODIUM SALTS                                                     OF SULFONATED POLYSTYRENES                                                    Material (mole %)                                                                          Polymer Level (g/l)                                                                          Viscosity (cps)                                   ______________________________________                                        3.0          0.12           280                                                            0.5            430                                                            1.0            480                                                            2.0            490                                               4.19         0.12           380                                                            0.25           440                                                            0.5            570                                                            2.0            820                                               6.05         0.12           420                                                            0.25           540                                                            0.5            820                                                            2.0            950                                               ______________________________________                                         *Viscosity measured with a Brookfield ® viscometer at 30 RPM.        

EXAMPLE 3

Due to the aqueous nature of the fluid within the thin membrane of thepseudo-emulsion particle, we observe dramatic changes in viscosity asthe shear rate is modified. Table IV shows the viscosity behavior of atypical pseudo-emulsion system in fresh water as a function of the rateof shear. At low shear rates, the viscosity is high, while a decrease isfound at higher shear. Furthermore, we observe a marked viscositydecrease as the overall shear rate is increased, which is typicalbehavior of all pseudo-emulsion systems (i.e. fresh, salt, acid or basicenvironments). In this particular example, an order of magnitudeviscosity change is found over a relatively modest shear rate range.Furthermore, we observe that this behavior is reversible (which again istypical behavior of a pseudo-emulsion system) within the shear raterange presented in this example.

                  TABLE IV                                                        ______________________________________                                        VISCOSITY - SHEAR RATE BEHAVIOR OF A TYPICAL                                  PSEUDO-EMULSION SYSTEM IN FRESH WATER                                                                         Viscosity                                     Material        Shear Rate (sec.sup.-1)                                                                       (cps)                                         ______________________________________                                        Sulfonated Polystyrene                                                                        0.4             470                                           (6.05 mole % - Sodium Salt)                                                                   0.8             390                                                           2.0             190                                                           4.0             120                                                           8.0             70                                                            16.0            68                                                            40.0            52                                                            79.0            45                                            ______________________________________                                    

It is evident from these discussions that this invention claims amarkedly different process and product than that described in someprevious patent applications (Ser. Nos. 223,482; 136,836; 106,027)covering the same class of polymers in similar mixed solvents. The priorapplications were specifically directed at gelation of a hydrocarbonphase by contact of mixed solvents with an aqueous phase and extractionof a water miscible cosolvent from the organic phase, thereby permittingassociation of the ionic groups and gelation. In this and copendingapplications, we claim viscosification of the aqueous phase. Such aclaim would certainly appear inconsistent and unexpected in view ofthose prior patent applications. This discussion will attempt to explainthese observations on a molecular scale.

We assume that the ionic polymers of this study are dissolved in anorganic diluent containing a polar cosolvent (alcohol) via selectedsolvation. The resulting ionic polymer is thereby homogeneouslydissolved without substantial aggregation. Now, if sufficient polymer ispresent (i.e. >1%) for a conventional high molecular weight polymer,there is an overlap of the polymer coils (i.e., they intermingle andentangle). Under these conditions, if the cosolvent is removed (i.e., bycontact with water), then the resultant aggregation of the ionic groupsresults in a total network or polymer gellation of the hydrocarbon phaseoccurs.

However, the unexpected observation which is the basis for the instantinvention is that, if the polymer concentration in the hydrocarbon phaseis less than 0.5% or so, the polymer coils no longer are in the overlapregime. Thus, entanglements between polymer chains do not obtain. Underthese conditions, contact of the solution with water does not result ingelation, but rather the polymer forms the pseudoemulsion phasedescribed herein. Thus, polymer concentration is the major variable anddominates which phase (aqueous or hydrocarbon) is viscosified.

What is claimed is:
 1. A process for forming a thickened aqueous fluidhaving a viscosity of at least about 50 cps which consisting essentiallythe steps of:(a) forming a solvent system of an organic liquid and apolar cosolvent, said polar cosolvent being less than about 15 weightpercent of said solvent system, a viscosity of said solvent system beingless than about 100 cps; (b) dissolving a water insoluble, unneutralizedor neutralized sulfonated polymer in said solvent system to form asolution, a concentration of said unneutralized or neutralizedsulfonated polymer in said solution being about 0.01 to less than 0.4weight percent, a viscosity of said solution being less than about 200cps; and (c) adding about 5 to about 500 volume percent water to saidsolution, said water being immiscible with said solution, with saidpolar cosolvent and said water insoluble, neutralized sulfonated polymertransferring from said organic liquid to said water causing theviscosity of said water to increase to at least 50 cps.
 2. A processaccording to claim 1 further including a means for removing said organicliquid from said aqueous fluid.
 3. A process according to claim 1,wherein said unneutralized or neutralized sulfonated polymer has about10 (free acid) to about 100 (10.4 mole % sulfonation) meq. of sulfonategroups groups per 100 grams of polymer.
 4. A process according to claim3 wherein said SO₃ H are neutralized within an ammonium or metalcounterion.
 5. A process according to claim 4 wherein said metalcounterion is selected from the group including antimony, tin, lead orGroups IA, IIA, IB or IIB of the Periodic Table of Elements.
 6. Aprocess according to claim 4 wherein said SO₃ H groups are at least 90mole percent neutralized.
 7. A process according to claim 1 wherein saidneutralized sulfonated polymer is formed from an elastomeric polymer. 8.A process according to claim 7 wherein said elastomeric polymer isselected from the group including EPDM terpolymer or Butyl rubber.
 9. Aprocess according to claim 1 wherein said neutralized sulfonated polymeris formed from a thermoplastic.
 10. A process according to claim 9wherein said thermoplastic is selected from the group includingpolystyrene, t-butyl styrene, ethylene copolymers, propylene copolymers,or styrene/acrylonitrile copolymer.
 11. A process according to claim 1wherein said polar cosolvent has a greater polarity than said organicliquid.
 12. A process according to claim 1 wherein said polar cosolventis selected from the group including aliphatic alcohols, aliphaticamines, di- or trifunctional aliphatic alcohols, water miscible amides,acetamides, phosphates, or lactones and mixtures thereof.
 13. A processaccording to claim 1 wherein said polar cosolvent is selected from thegroup including methanol, ethanol, propanol, isopropanol and mixturesthereof.
 14. A process according to claim 1 wherein said polar cosolventhas a solubility parameter of at least about 10 and is water miscible.15. A process according to claim 1 wherein said organic liquid isselected from the group including aromatic hydrocarbons, ketones,chlorinated aliphatic hydrocarbons, aliphatic hydrocarbons, cyclicaliphatic ethers, aliphatic ethers or organic aliphatic esters andmixtures thereof.
 16. A process according to claim 1 wherein saidorganic liquid is selected from the group including aliphatichydrocarbons or aromatic hydrocarbons.
 17. A process according to claim1 wherein said organic liquid is selected from the group includingbenzene, toluene, ethyl benzene, xylene or styrene and mixtures thereof.18. A process according to claim 17 wherein said neutralized sulfonatedpolymer is formed from polystyrene.
 19. The product prepared by theprocess of claim 1.